Integrated circuit fabrication frequently includes formation of conductive materials directly against semiconductor materials. Example semiconductor materials are silicon and germanium.
Semiconductor materials may be considered part of semiconductor substrates. To aid in interpretation of this disclosure, the terms “semiconductive substrate” and “semiconductor substrate” are defined to mean any construction comprising semiconductive material, including, but not limited to, bulk semiconductive materials such as a semiconductive wafer (either alone or in assemblies comprising other materials thereon; with an example semiconductive wafer being a monocrystalline silicon wafer), and semiconductive material layers (either alone or in assemblies comprising other materials; with an example semiconductive material layer being a layer of polysilicon). The term “substrate” refers to any supporting structure, including, but not limited to, the semiconductive substrates described above.
Integrated circuitry may include conductively-doped regions of semiconductor material. Such regions may be n-type doped or p-type doped. Electrical interconnects may be formed to electrically contact the conductively-doped regions.
One method of forming an electrical interconnect to a conductively-doped region is to form titanium silicide directly against the semiconductor material of the region, to form a metal nitride cap over the titanium silicide to protect the titanium silicide from oxidation, and to then form a conductive pedestal in electrical contact with the electrically conductive metal nitride cap. The metal nitride cap may comprise, for example, titanium nitride.
If the semiconductor material comprises silicon, the titanium silicide may be formed by depositing titanium directly against the silicon, and then reacting the titanium with the silicon to form titanium silicide.
The deposition of the titanium may be conducted on a substrate having some regions where titanium is desired to be deposited, and other regions where titanium deposition is not desired. For instance, the substrate may comprise electrically insulative regions (for instance, silicon dioxide regions or silicon nitride regions) in addition to the semiconductor regions, and it may be desired to form the titanium on the semiconductor regions but not on the insulative regions. It is difficult to form the titanium only over desired regions, and accordingly it is desired to develop improved processing for titanium deposition.
In addition to applications in which it is desired to deposit titanium selectively over one surface relative to another, there are also applications in which it is desired to form titanium-containing films uniformly across numerous surfaces of differing compositions. For instance, it may be desired to form a wiring layer extending across a conductively-doped region of semiconductor material, and also across insulative material surfaces adjacent the conductively-doped region. It can be difficult to form titanium-containing materials uniformly across semiconductor surfaces and insulative material surfaces, and accordingly it is desired to develop improved processing for titanium deposition that can be suitable for such applications.